With all the hormones and whatnot inside. Dopamine, adrenaline, melatonin, whatever. Also, there’s this Hunter S. Thompson bit on the… pineal gland?
If it had an effect on you, wouldn’t it be a really messed up high, all over the place? With uppers, downers etc mixed? (Not including the emotional implications of eating raw human brains.)
Specifically a spongiform encephalopathy. Completely incurable and universally fatal. If you contract a prion disease medical science can only ever prolong the inevitable, and it is extremely unlikely that will ever change barring some unknown hyper futuristic nano-machine technology.